Modeling the Radiolysis of Supercritical Water by Fast Neutrons: Density Dependence of the Yields of Primary Species at 400°C

2014 ◽  
Vol 182 (6) ◽  
pp. 695-704 ◽  
Author(s):  
Sofia Loren Butarbutar ◽  
Jintana Meesungnoen ◽  
David A. Guzonas ◽  
Craig R. Stuart ◽  
Jean-Paul Jay-Gerin
Keyword(s):  
Density Dependence ◽  
Supercritical Water ◽  
Fast Neutrons

Radiolysis of Supercritical Water at 400°C: A Sensitivity Study of the Density Dependence of the Yield of Hydrated Electrons on the (eaq−+eaq−) Reaction Rate Constant

2016 ◽  
Vol 2 (2) ◽  
Author(s):  
Sunuchakan Sanguanmith ◽  
Jintana Meesungnoen ◽  
David A. Guzonas ◽  
Craig R. Stuart ◽  
Jean-Paul Jay-Gerin
Keyword(s):  
Temperature Dependence ◽  
Density Dependence ◽  
Rate Constant ◽  
Supercritical Water ◽  
Reaction Rate ◽  
Reaction Rate Constant ◽  
Sudden Drop ◽  
Alkaline Water ◽  
Hydrated Electrons ◽  
Neutral Water

The temperature dependence of the rate constant (k) of the bimolecular reaction of two hydrated electrons (eaq−) measured in alkaline water exhibits an abrupt drop between 150°C and 200°C; above 250°C, it is too small to be measured reliably. Although this result is well established, the applicability of this sudden drop in k(eaq−+eaq−)) above ∼150°C to neutral or slightly acidic solution, as recommended by some authors, still remains uncertain. In fact, the recent work suggested that in near-neutral water the abrupt change in k above ∼150°C does not occur and that k should increase, rather than decrease, at temperatures greater than 150°C with roughly the same Arrhenius dependence of the data below 150°C. In view of this uncertainty of k, Monte Carlo simulations were used in this study to examine the sensitivity of the density dependence of the yield of eaq− in the low–linear energy transfer (LET) radiolysis of supercritical water (H2O) at 400°C on variations in the temperature dependence of k. Two different values of the eaq− self-reaction rate constant at 400°C were used: one was based on the temperature dependence of k above 150°C as measured in alkaline water (4.2×108  M−1 s−1), and the other was based on an Arrhenius extrapolation of the values below 150°C (2.5×1011  M−1 s−1). In both cases, the density dependences of our calculated eaq− yields at ∼60  ps and 1 ns were found to compare fairly well with the available picosecond pulse radiolysis experimental data (for D2O) for the entire water density range studied (∼0.15–0.6  g/cm3). Only a small effect of k on the variation of G(eaq−)) as a function of density at 60 ps and 1 ns could be observed. In conclusion, our present calculations did not allow us to unambiguously confirm (or deny) the applicability of the predicted sudden drop of k(eaq−+eaq−) at ∼150°C in near-neutral water.

Water density dependence of formaldehyde reaction in supercritical water

2004 ◽  
Vol 28 (2-3) ◽  
pp. 219-224 ◽  
Author(s):  
Mitsumasa Osada ◽  
Masaru Watanabe ◽  
Kiwamu Sue ◽  
Tadafumi Adschiri ◽  
Kunio Arai
Keyword(s):  
Density Dependence ◽  
Supercritical Water ◽  
Water Density

Radiolysis of supercritical water at 400 °C: density dependence of the rate constant for the reaction of hydronium ions with hydrated electrons

2019 ◽  
Vol 21 (18) ◽  
pp. 9141-9144 ◽  
Author(s):  
Jintana Meesungnoen ◽  
Jean-Paul Jay-Gerin
Keyword(s):  
Density Dependence ◽  
Rate Constant ◽  
Supercritical Water ◽  
Water Density ◽  
Hydronium Ions ◽  
Hydrated Electrons

The rate constant, k(eaq− + H3O+), for the reaction of hydronium ions with hydrated electrons in supercritical water at 400 °C has been evaluated as a function of water density over the range of 0.15–0.6 g cm−3.

Self-radiolysis of tritiated water. 2. Density dependence of the yields of primary species formed in the radiolysis of supercritical water by tritium β-particles at 400 °C

RSC Advances ◽  
2014 ◽  
Vol 4 (44) ◽  
pp. 22980 ◽  
Author(s):  
Sofia Loren Butarbutar ◽  
Sunuchakan Sanguanmith ◽  
Jintana Meesungnoen ◽  
Patrick Causey ◽  
Craig R. Stuart ◽  
...  
Keyword(s):  
Density Dependence ◽  
Supercritical Water ◽  
Tritiated Water
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